NOT Operator

[aaronik19]

Dear Friend,

I do not know what is happening with the part of the program I am using. I have a variable containing a byte 0b01001011 and in a sub-function I have another variable which will hold the inverse value.

[Ttelmah]

Problem is that "!=", is the logical inequality operator. If you look at the list of operators that allow you to 'shortcut' arithmetic with assignment, you have:
+= /= %= += -- <<= >>= &= ^= |=

!, can't be used this way. So what the code is doing, is comparing variable1 with variable2, and throwing away the result (so has no effect).

Best Wishes

[aaronik19]

so how I can achieve my code please?

[RF_Developer]

In C the bitwise inversion operator is ~. As in

variable2 = ~variable1;

alternatively you can exclusive or with all ones, or any other bit pattern to invert some bits in a variable:

invert all bits in int:
variable2 = variable1 ^ 0b11111111;

invert lower four bits only:
variable2 = variable1 ^ 0b00001111;


RF Developer

[Ttelmah]

variable2 = (!variable1);

Which separates the inversion from the assignment.

Best Wishes

[Ttelmah]

Yes, as RF_developer says from what you show you want the bitwise not operator, 'not' the logical not anyway!....

Also, it is key to understand the difference between (for instance):

val+=1;

val= +1;

The first adds 1 to val, and is a 'shortcut' for:

val=val+1;

The second assigns the number +1 to val.

Best Wishes

[bkamen]